Site Factor on Nutritional Content of Arundinaria Alpina and Oxytenanthera Abyssinica Bamboo Shoots in Ethiopia

Full Length Research Paper

Site factor on nutritional content of Arundinaria alpina and Oxytenanthera abyssinica bamboo shoots in Ethiopia

Sisay Feleke

Ethiopian Institute of Agricultural Research, Forest Products Utilization Research Coordination, P. O. Box 2322, Addis Ababa, Ethiopia.

Accepted 29 July, 2013

The objective of this study was to characterise some of the nutritional values of the two bamboo species grown and consumed in western parts of Ethiopia. The bamboo shoots of each the two species were collected from each of the three sites and analyzed for their nutritional and mineral composition. The average moisture content of the bamboo shoots was more than 90% for both species but the fat content as determined on dry weight basis indicated a significant variation ranging from 0.6 to 2.2% for Oxytenanthera abyssinica and from 0.6 to 1.5% for Arundinaria alpina. Highland bamboo (A. alpina) shoots characterized with high nitrogen content (5.40%) implying that they may have high content of protein, but the lowland bamboo (O. abyssinica) was low in nitrogen content (3.10%). The average ash contents of the highland bamboo shoots collected from Tekur Incheny, Enjibara and Masha site were 14.20, 15.50 and 17.20%, respectively. The average nutrient elements in the shoots of O. abyssinica were in the order of K>N>P>Ca>Mg, whereas in A. alpina bamboo shoots observed to have slight variation in the arrangement of these elements with the order of K>N>P> Mg > Ca.

Key words: Arundinaria alpina, Oxytenanthera abyssinica, bamboo shoots, mineral elements, nutrients.

INTRODUCTION

Bamboo is a perennial grass with over 1200 species in Ethiopia has two bamboo species: The African alpine 50 genera of bambuosidaea and grows mainly in the Bamboo Arundinaria alpina (K. Schumann Lin) which tropics and subtropics (Zhang et al., 2002). In different grows between 2200 and 4000 m above sea level (asl) parts of the world, it is used as a source of raw material and the lowland bamboo Oxytenanthera abyssinica (A. for fodder, construction materials, paper production, Richard Munro) which grows between 1200 and 1800 m laminated boards, energy, food, beverage and medicine asl (Sylvia, 1995; Embaye et al., 2005). In Ethiopia the (Choudhury et al., 2010). The bamboo shoots have been common use of bamboo resource is limited to fencing, used as food for centuries in Asia. Their protein content is house construction (tukul), waving, household furniture as high as 1.49 to 4.04% with 17 kinds of essential amino and utensils but there are the experiences of bamboo acids accounting for 35% of the total protein. They are shoots consumption in the western and south western also rich in other mineral nutrients which are highly parts of Ethiopia. In general, the most common use of valuable for human being (Hunter and Feng’e, 2000; bamboo is for the construction purposes. The area Choudhury et al., 2010). coverage of bamboo in the country is reported to vary

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from eight hundred thousand to one million ha (FRA, found in northwest Ethiopia (11° 09' N and 36° 03' E) and has an 1985; Embaye et al., 2003) but currently this figure may altitude of 1120 m asl and mean annual rainfall of 1587 mm. be reduced due to the expansion of mechanised Didhessa is located in the south-western of the country (8°41’ N and 36°24’ E) at the altitude of ~ 1300 m asl. Assosa is located in agriculture in bamboo growing parts of the country. the western region of the country (10°7’ N and 34°37’ E) with an Recently, in response to the growing interest of utilizing altitude of 1510 m asl. the existing bamboo resource, some research activities have been going on in areas such as product characterization and different management options Sample preparation

(Embaye et al., 2003, 2005; Seyoum et al., 2006, 2007). Lowland bamboo shoots (O. abyssinica) were collected from In Ethiopia Bamboo shoots (BS) usually emerge after Asossa, Pawe and Dhidhessa while the highland bamboo shoots the spring rain, namely between April and June without (A. alpina) collected from Enjibara, Masha and Tikur Enchiny. Shoot disregarding its dependence on location and species. samples of both bamboo species were transported to the laboratory The quality of bamboo shoots for food depends on the under liquid nitrogen to avoid spoilage of the shoots. biological characteristics of the bamboo such as species, The outer cover of the hard sheath, the bottom and top portions of the shoots were removed by hand and the remaining middle shooting time, duration of shooting, the rate of shoot portions (the edible part of the shoots) which account for 45% of the growth and the size of shoots. emerging ones were washed three times in cold water, sliced at the Bamboo shoots are known for their low fat and thickness of 5 mm and then dried at a temperature of 45°C using cholesterol content and high content of protein, mineral oven drier for 40 h. and dietary fibre. Reports show that some species of BSs like other root crops such as cassava, have some Moisture content cyanogenic glycoside composition which decrease following harvesting of the material and during the time of The moisture content of the bamboo shoots were determined by food preparation (Anonymous, 2004; Agatemor, 2009; drying of the samples in an oven at 105 ± 2°C. Choudhury et al., 2010, 2012). Bamboo has an immense potential in realizing the food Fat extraction security mechanism of the country. To achieve such objective, the indigenous knowledge of bamboo shoots The bamboo shoots were extracted with hexane in a Soxtec consumption which accumulated over centuries can be apparatus (a product of Germany) and the average reading of six easily introduced to other bamboo growing and potential replicate for each location were taken (Greenfield and Southgate, areas. However, dissemination of such indigenous 2003). knowledge can be effective only when preceded by some improvement works which include taste and preparation Ash determination ease that lead to getting fast adoption rate in the community. The traditional methods of preparing food A sample of the bamboo shoots was first heated on a burner in air from bamboo shoots by the indigenous people (ethnic to remove its smoke, and then burned in a furnace at 550°C. The community) of south western and western parts of ash content was expressed as a percentage ratio of the weight of Ethiopia demands some improvement work, especially the ash to the oven dry weight of bamboo shoots. with regard to nutritional analysis, the removal of the natural toxicants or bitterness prior to consumption and Nitrogen content storability. The objective of this paper was to identify and raise Nitrogen analysis was undertaken using Kehdjal Distillation awareness on some of the parameters of the nutritional Apparatus. The amount of nitrogen was calculated by the amount of acid added that change the colour of the distilled solution. The values of bamboo shoots of O. abyssinica and A. alpina protein content was calculated using the nitrogen conversion factor species that used for food in south western and western (NCF) of 6.25 (Anonymous, 1998). parts of Ethiopia.

Mineral content

MATERIALS AND METHODS Ash obtained from samples of bamboo shoots were dissolved in concentrated sulfuric acid. Then the solution was used for the Site description determination of the studied minerals by Atomic Absorption Spectrometer except for Phosphorous. Wet ash method was used The samples of bamboo shoots are collected from the following six for the determination of Phosphorous. Finaly the amount of sites. Masha forest which located in southwest Ethiopia (7° 30’N; Phosphorous was determined using UV-VIS spectrometer at 400 35° 30’E) has an altitude that ranges from 2400 to 3000 m asl, nm wave length (AOAC, 2000). mean annual rainfall of over 2300 mm and annual temperature range 16 to 20°C (Embaye et al., 2005). Enjibara is located in northern parts of the country (10°56’ N and 36°56’E) at elevation of Statistical analysis 2560 m asl. Tikur Inchini is situated in western parts of the country (9°19’ N and 38°24’ E) and has an altitude of 2700 m asl. Pawe Results were expressed as the mean of three replicates. A one-way Feleke 117

Table 1. Mean nutritional values of Arundinaria alpina.

Location Components Injibara Masha Tikur Incheny Nitrogen (%) 5.83a 6.22a 4.15b Fat (%) 1.1a 0.64b 1.5a Moisture (%) 93.3a 93.0a 91.9a Ash (%) 15.6b 17.1a 14.2c P (ppm) 9660a (0.97%) 9903.33a (0.99%) 7113.33 b (0.71%) K (ppm) 90833.33b (9.08%) 97716.67a (9.77 %) 85350.00c (8.54%) Ca (ppm) 2440.00a (0.24%) 2853.30a (0.29%) 1633.33b (0.16%) Mg (ppm) 1890.00a (0.19%) 1850.00a (0.19%) 1386.67b (0.14%) Fe (ppm) 72.67b 147.00a 41.67c Mn (ppm) 25.33a 28.33a 11.00b Zn (ppm) 107.00b 210.67a 97.67b

Means with similar letters for comparison between different sites are not significantly different at p = 0.05.

analysis of variance (ANOVA) was used to compare the mean respectively. The high amount of ash reveals the mineral using the least significant difference at 5% level. richness of the biological material which serves as a source of mineral elements required in the nutrition. Whereas the average ash content for the lowland RESULTS AND DISCUSSION bamboo shoots collected from Assosa, Dhidhessa and Pawe were 11.17, 12.03 and 11.63% dwb, respectively. In Masha and Assosa areas where the bamboo shoots The lowest ash content in the lowland bamboo was emerge between April and June the indigenous obtained from Assosa (10.87% dwb) and the highest was communities use it as a food during spring season of the obtained from Dhidhessa (12.38% dwb) areas. The ash year. The shoots are immediately picked within the first amount of the lowland bamboo from Dhidhessa site week of their development as they have a growth rate of showed a significant difference from that of Assosa up to 1 m per day for some species (Anonymous, 2004). sample (Table 2). High amount of ash also reported on Before serving, the shoots are boiled and drained the first bamboo shoots of Fargesia yunnanensis (Wang et al., water to reduce the bitterness or the toxic chemicals of 2009). High ash content of biological material is also the shoots which could be the cynogenic glycosides observed in barks and annual crops, indicating that it is a (Hunt and Feng’e, 2000; Agatemore, 2009; Choudhury et phenomenon for fast growing plants, which can al., 2010, 2012). accumulate high amount of mineral materials in the In both shoot samples Ethiopian bamboo species the growing season (Raveendran et al., 1995; Azarov et al., fat extract has a light yellow colour. The bamboo shoots 1999). Similar with the BSs of Bambusa balcoa, Bambus of A. alpina were low in fat content with an average of polymorpha, Dendrocalmus hamiltonii, D. strictus, D. 1.09% on dry weight basis (dwb). The statistical analysis gigantus, Phyllostachys praecox the ash content of the of the fat content showed that the samples of Masha site studied species are high but their mineral contents was lower in fat content which differ significantly from the depend on the species, location and season of harvesting contents of the samples of the other two locations (Table (Zhang et al., 2011; Chouduhry et al., 2011). The high 1). The average fat content of the lowland bamboo amounts of ash content in the bamboo shoots enable shoots collected from Assosa, Dhedhessa and Pawe them to hold the macro- and micro-elements making sites was 1.44% on dwb. The average fat content of them preferable. shoots collected from Pawe area was significantly The average nitrogen content of the bamboo shoots of different from those of the other two locations. The low fat A. alpina from Tekur Incheny, Injebara and Masha areas content in bamboo shoots is also reported by others and were in the range of 4.15 to 6.22% dwb. The lowest this is one of the reasons that make the bamboo species amount was 4.15% dwb and the highest was 6.22% dwb as a preferred food items (Choudhury et al., 2010, 2011). from Tekur Incheny and Masha areas, respectively. The The mean ash content of highland bamboo shoots nitrogen content of the bamboo shoots from Tekur collected from the three sites range from 14.20 to 17.10% Incheny site was low and significantly different from those dwb. The ash content of the highland bamboo shoots of the other two locations (Figure 1). The average was significantly varied with locations. The lowest ash nitrogen content in A. alpina bamboo shoots are 8 to 10 amount of the shoot was 14% dwb and the highest was times richer than the 1st to 3rd year old culms of Masha 18% dwb for samples of Tekur Incheny and Masha, area (Embaye et al., 2005). Such high variation in nitrogen 118 J. Hortic. For.

Table 2. Mean nutritional values of Oxytenanthera abyssinica.

Location Components Assoa Dehdhesa Pawe Nitrogen (%) 3.30a 3.99a 2.96a Fat (%) 1.5a 2.2a 0.6b Moisture (%) 91.65a 92.57a 92.54a Ash (%) 11.17b 12.03a 11.63ab P (ppm) 5686.67c (0.57%) 6166.67b (0.62%) 7453.33a (0.75%) K (ppm) 66285b (6.63%) 70283.33a (7.03%) 71533.33a (7.15%) Ca (ppm) 933.33c (0.09%) 1200.00b (0.12%) 1460.00a (0.15%) Mg (ppm) 1903.33a (0.19%) 2020.00a (0.20%) 1986.67a (0.20%) Fe (ppm) 33.67c 45.00b 88.00a Mn (ppm) 19.67a 19.33a 18.67a Zn (ppm) 71.67c 88.33b 106.67a

Means with similar letters for comparison between different sites are not significantly different at p = 0.05.

Phosphorous content in bamboo Calcium content in bamboo shoots of A.alpina shoots of A.alpina 1.20 0.35 a a a 1.00 0.30 a 0.80 b 0.25 0.60 0.20 b 0.40 0.15

P amount, % amount, P 0.20 0.10 Ca amount, % amount, Ca 0.00 0.05 Tikur Enjibara Masha 0.00 Inchine Tikur Inchine Enjibara Masha Location Location

Potassium content in bamboo shoots of A.alpina 10 a 9.5 b 9 c 8.5

K amount, % amount, K 8 7.5 Tikur Inchine Enjibara Masha Location

Figure 1. Mineral contents in bamboo shoots of A. alpina from different locations. Bars with the same letter are not significantly different at p = 0.05 level.

content is attributed to the active and fast growing stage collected from the three locations. When the nitrogen of the plant which requires more nitrogen in the content in the shoots multiplied by the factor 6.25 the chlorophyll make up, cell differentiation of the growing total protein amount ranges between 2.88 and 4.13% of bamboo shoots and biosynthesis of nitrogen containing the fresh BS which is in the range of other BS of Asian compounds. The average nitrogen content for lowland species (Wang et al., 2009; Chouduhury et al., 2010, bamboo shoots was 3.29, 3.99 and 2.95% dwb for 2011). samples from Assosa, Dhidhessa and Pawe areas, The average phosphorous content of the A. alpina respectively. There was no significant difference in bamboo was 0.71, 0.97 and 0.99% for samples collected nitrogen content between the lowland bamboo shoots from Tekur Incheny, Injebara and Masha sites, Feleke 119

Phosphorous content in bamboo Calcium content in bamboo shoots shoots of O.abyssinica of O.abyssinica 0.80 a 0.20 b c a 0.60 0.15 b c

0.40 0.10 P amount, % amount, P

0.20 % amount, Ca 0.05

0.00 0.00 Assosa Dhedhesa Pawe Assosa Dhedhesa Pawe Location Location

Magnesium content in bamboo Potassium content in bamboo shoots of O.abyssinica shoots of O.abyssinica a 0.21 7.20 a a a 0.20 7.00 6.80 0.20 b a 6.60 0.19

P, amount, % amount, P, 6.40 Mg amount, % amount,Mg 0.19 6.20 Assosa Dhedhesa Pawe Assosa Dhedhesa Pawe Location Location

Figure 2. Mineral contents in bamboo shoots of O. abyssinica. Bars with the same letter are not significantly different at p = 0.05 level.

respectively. The phosphorous amount in the highland the samples of Assosa area (Table 2). In both studied bamboo shoots from Tekur Incheny was significantly species, the calcium content accounts for less than 1% of different from Injebara and Masha locations with its low the mineral content unlike the perennial plant wood which content. Similarly, the average phosphorous content of consists more than 50% (Fengel and Wegner, 1984; the samples of lowland bamboo shoots of Assosa, Azarov et al., 1999). Dhidhessa and Pawe were 0.57, 0.62 and 0.75%, The average magnesium contents of A. alpina bamboo respectively. The result of phosphorus content indicates shoots collected from Tekur Incheny, Injebara and Masha strong differences between all the three locations. The was in the range of 0.14 to 0.19%. The highland bamboo phosphorous content of BSs of A. alpina and O. shoots of Tekur Incheny site exhibited lowest amount abyssinica is much higher than those of Bambusa and which was significantly different from those of Injebara Dendrocalamus species (Choudhury et al., 2010, 2011). and Masha locations as indicated in Figure 1. On the The average calcium content of the bamboo shoots of other hand, the average magnesium content in the A. alpina was analyzed and found the lowest content in shoots of O. abyssinica collected from Assosa, the samples of Tekur Incheny site which was statistically Dhidhessa and Pawe areas was in the range of 0.19 to different from those of Injebara and Masha areas. The 0.20% with no significant difference between locations average calcium contents were 0.16, 0.24 and 0.29% for (Figure 2). The amount of magnesium in these bamboo bamboo shoot samples of Tekur Incheny, Injebara and shoots were 10 fold higher than the leafy vegetables of Masha areas, respectively (Table 1). The low calcium Amaranthus spinosus, Hibiscus species, Solanum content of the samples of Tekur Incheny is related to the macrocarpon consumed in Northern Ghana (Amagloh low ash content of the sampled material. The average and Nyarko, 2012) and equal to Eragrostis tef an calcium content of the lowland bamboo shoot samples of Ethiopian staple food called “Injera” made of it (Seyfu, O. abyssinica collected from Assosa, Dhidhessa and 1997; Parish, 2006). Pawe areas were 0.09, 0.12 and 0.15%, respectively. The average potassium contents in the bamboo shoots There was significant difference between the sites in of A. alpina were 8.53, 9.08 and 9.77% for the samples of average calcium content the lowest calcium content in Tekur Incheny, Injebara and Masha areas respectively. 120 J. Hortic. For.

The statistical analysis for the average potassium content and Agricultural Development of the districts targeted for showed significant differences among all three sites. materials, to his assistants Ato Kinfe Tesfaye and Ato Whereas the average potassium content in O. abyssinica Ayeshem Tebeje and also extend his thanks to the bamboo shoots collected from Assosa, Dhidhessa and anonymous reviewers for their valuable and constructive Pawe areas were 6.63, 7.02 and 7.15%, respectively. comments on previous version of this paper. The average potassium content of the samples of Assosa site was found to be lower and significantly different from those of the other locations. There are also reports which REFERENCES reveal similar high amounts of potassium in bamboo Agatemor C (2009). Cooking time and steeping time effects on the shoots of other species (Shanmughavel and Francis, cyanide content and sensory quality of cassava slices. Electronic J. 2003; Choudhury et al., 2011). 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